Samhain is a Gaelic festival marking the end of the harvest season and the beginning of winter or the "darker half" of the year. Traditionally, it is celebrated from 31 October to 1 November, as the Celtic day began and ended at sunset. This is about halfway between the autumn equinox and the winter solstice. Over time, Samhain and All Saints'/All Souls' merged to create the modern Halloween. Historians have used the name 'Samhain' to refer to Gaelic 'Halloween' customs up until the 19th century.